Data is often input to computers or processors using optical input systems. One rapid method of inputting data into a processor employs bar code symbologies, where data is encoded in varying widths, bars, and spaces. An optical input system such as an LED pen or laser scanner provides information to the processor of a bar code reader, where the information represents the widths of the bars and spaces.
The processor in turn decodes these widths into appropriate data characters. To improve information density, linear bar code symbologies are being replaced by two-dimensional bar code symbologies. Two-dimensional symbologies, as opposed to traditional bar code symbologies, encode data in two directions. While two-dimensional symbologies, such as PDF417, can be read and decoded using a laser scanner, most two-dimensional symbologies require a two-dimensional image to be captured, digitized and analyzed. For example, a two-dimensional charge-coupled device (CCD) produces a series of electrical signals that represent an image, much like a digital photograph. A processor then stores and analyzes the digital image to locate and decode a two-dimensional symbol located within the image.
Laser scanners in point-of-sale terminals are specifically designed to rapidly decode linear bar code symbols (particularly UPC symbols) on products. Such laser scanner point-of-sale terminals can read only bar code symbols, and typically only bar code symbols selected from a preprogrammed symbology. Readers for two-dimensional symbologies are more complex, because they must identify at least one type of two-dimensional symbology within a field of background noise (e.g. text). While two-dimensional readers can decode a larger number of machine-readable symbologies, such two-dimensional readers are restricted to inputting and decoding machine-readable symbologies.
An operator of a reader or a cashier at a point-of-sale terminal must manually input any additional information into a reader or cash register by either receiving verbal information from a customer or reading data from a document (e.g., coupon), and then manually inputting the data. Other input devices are necessary to input additional data, such as card readers for reading magnetic stripes on credit cards.